1. Field
The present disclosure relates to the field of communication technologies, and in particular to a bit allocation method, apparatus for a multicarrier modulation signal, and system.
2. Description of the Related Art
Multicarrier modulation uses multiple subcarrier signals, in which a data stream is divided into some sub-data-streams, so that the sub-data-streams have much lower transmission rates, and such data are used respectively to modulate some subcarriers. A multicarrier modulation signal is featured in relatively low data transmission rate, and in relatively long symbol period, etc. The multicarrier modulation may be achieved in multiple technical ways, such as Discrete Multi-tone (DMT), and Orthogonal Frequency Division Multiplexing (OFDM), etc. Fast Fourier Transform (FFT) is an effective method for achieving multicarrier modulation.
A problem existing in a multicarrier modulation signal is that its Peak to Average Power Ratio (PAPR) is relatively high. In practical application, a peak value of signals outputted by a transmitter is usually limited. Hence, in order to increase average power of the signals, the PAPR of the signals needs to be lowered, wherein, a most often used method is to perform clipping on a multicarrier modulation signal. Signal distortion is introduced by the clipping method while the PAPR is lowered and the average power of the signal is increased. And on the other hand, as a multicarrier modulation signal is formed by superimposing multiple subcarrier signals, in some particular bit patterns, an extremely high PAPR will occur, and a clipping operation of of symbols of the extremely high PAPRs will produce extremely high signal distortion, thereby resulting in burst error in the symbols. Although the probability of occurrence of such a burst error is not high and has little effect on an average bit error rate, such a burst error will result in invalidation of Forward Error Correction (FEC) decoding, and hence result in communication failure.
It should be noted that the above description of the background is merely provided for clear and complete explanation of the present disclosure and for easy understanding by those skilled in the art. And it should not be understood that the above technical solution is known to those skilled in the art as it is described in the background of the present disclosure.